I. Field of the Invention
The invention generally relates to mechanisms for preventing flooding or overflows in holding tanks and receptacles. The invention more particularly relates to preventing overflows in toilets of the type used in prisons or other institutions, however, the invention is capable of significantly wider application.
II. Description of the Prior Art
In recent years, greater attention has been paid to the expansion and renovation of prisons and other correctional facilities. It has been the experience in such facilities that inmates will sometimes attempt to disrupt normal operations by stuffing clothes or other objects into a toilet bowl and by repeatedly flushing the toilet to cause its flooding. This can result in substantial property damage, and if the living units in which the toilets are located are on an upper floor, the overflow may find its way to offices, archives or other areas below. Toilets in such facilities must be tamper-resistant in order to prevent these occurrences.
Various devices have been proposed to prevent either accidental or deliberate flooding of toilets. For example, in Ringler, U.S. Pat. No. 4,041,557, an electrode is positioned in a fill line leading to a toilet bowl. The fill line is located at an elevation corresponding to the desired water level so that if the water exceeds this level, the excess water level will be sensed. The electrode will generate a signal to open a pair of normally closed contacts, which are connected as part of an electrical circuit between the flush actuator and an electrically operated flush control valve. This type of electrical system is relatively expensive as a result of the safety restrictions that arise when electrical elements are used around water and conductive materials in the vicinity of a human body.
Albertson, U.S. Pat. No. 3,928,,874 shows another type of overflow inhibitor mechanism in which a flood-operated switch element is located inside a toilet bowl to provide an electrical signal to a solenoid-actuated valve. This valve can be positioned in either a water supply line or in a line connecting a holding tank to the toilet bowl. A third alternative is disclosed in which a water pressure sensing switch is used to operate a solenoid for jamming the flush handle. Each of these three mechanisms would be easily defeatable in the institutional environment described above, because they assume that the toilet has an exposed reservoir tank that would render the flush mechanism accessible to the user. The disadvantage related to the and cost of electrically actuated control systems is also applicable to the Albertson devices.
While provision of a mechanically actuated flood preventer overcomes some of the disadvantages of the electrical systems, there are other technical problems posed by their mechanical actuators. For example, there is a certain amount of variation or tolerance in the dimensions of mechanical parts that must be accounted for. Otherwise, a mechanical disabling device might only partially disable a flush control valve, so that the valve could be actuated a second time if its manipulation was studied long enough.
There is also a need to provide a mechanical disabling mechanism that can be adapted to and used with flush control valves and actuators that are now commercially available. It would be a disadvantage if the use of a flood prevention mechanism required substantial modification of commercially available flush valves, or the design of custom flush valves.